Balance-staff.



No. 744,719. PATENTED NOV. 2A, 1903.

1). H. CHURCH. BALANCE STAFF.

APPLICATION FILED JAN. 31,1602.

N0 MODEL.

UNITED STATES Patented November 24, 1903.

DUANE IT. CHURCH, OF NEWTON, MASSAGEUSE'ITS BALANCE-STAFF.

SPECIFICATION forming part of Letters Patent No. 744,719, dated November 24, 1903.

Application filed January 31, 1902. Serial No. 91,964. (No model.)

To aZZ wit/0711, it may concern:

Be it known that I, DUANE H. CHURCH, of Newton, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Balance-Staffs, of which the following is,a specification.

This invention has relation to pocketwatches, and more particularly to the staffs or arbors for the balances thereof.

In pointing out the object of the invention it is necessary to refer to the well-known fact that to reduce the running friction of an arbor to a minimum the pivots thereof must be made as small in diameter as possible and that they are of necessity weak and liable to breakage not only during the manufacture of the watch, but while it is in use. Hence it is the practice to reduce this element of weakness by forming the pivots with no abrupt shoulders, such as are common to the pivots of other members of the watch-train.

It is essential that the balance-wheels of Watches be firmly fixed on their staffs and that these wheels shall run absolutely true both in the round and in the fiat. The ordinary method of attaching the balancewheel to its staff is to form the staff with a relatively large portion to fit the axial hole of the wheel, the face of which rests against a shoulder of the balance-staff, and that portion of the staff which fits the hole is made a little longer than the thickness of the balance-arms, to allow of staking or riveting the two members firmly together. An unfortunate condition consequent upon this method of attaching the balance and its staff is the difficulty of removing a broken staff and replacing it bya new and perfect one, since there is danger that in removing the broken staff, which had been firmly staked to the balance, the hole will become injured or enlarged, so that the. new staff will fail to fit so as to insure the truth of the balance.

Balances have been made with a hub projecting on each side, to which hub on one side was attached the colletof the hair-springand on the'other side the roller-table, with its jewel-pin, to actuate the pallet lever or fork. These hubs had a straight or slightly-tapering axial hole, into which fitted a balancestafi made without any shoulders to govern or fix the position of the balance, which position was obtained by driving or forcing the balance-arbor back and forth until the correct position was obtained, which involved numerous trials and examinations. A very serious difficulty involved in the above method lies in the absence of any shoulders to receive the pressure needful to force the staff in either direction, as it is manifest that the extreme delicacy of the pivots precludes the use of any force at those points.

The object of my invention is to secure the very great advantage of being able to separate the balance from the staff and to apply another staff without danger of injury to the balance, at the same time avoiding the necessity of a retruing of the balance. These results I obtain by the form of construction illustratedin the accompanying drawings and now to be described in detail and finally pointed out in the claims hereto appended.

In the said construction, which embodies one form of my invention, the staff is removable from the balance and is formed with an enlargement which provides an abrupt shoulder to receive a tool by means of which the disengagement of the staff and balance is effected. The enlargement has also a peripheral flange which provides a face to be engaged by the end of a hub or collet, the latter having a tapering aperture adapted to receive said enlargement. The engagement between the hub or collet and the staff is in a line at the smaller end of the aperture in the collet, whereby the other end of the latter may be moved laterally relatively to the staff to adjust it squarely against the shoulder, said engagement preventing, however, the withdrawal of the collet except when considerable pressure is applied thereagainst.

On the drawings similar letters refer to similar parts or features, as the case may be, wherever they occur.

Of the said drawings, Figure 1 represents in sectional View a balance and its staff in which my invention is embodied. Fig. 2 represents a similar section through another form of the invention.

The balance is indicated at a upon the draw ings and is provided with a central tapering aperture to, which is relatively large in diameter to receive the tapering boss I) of the hub or coilet b. The metal of the boss I) is upset, as at W, to secure the hub or collet rigidly to the balance after it has been adjusted, the latter having a shoulder to abut against the balance, whereby it is easily trued. Extending centrally through the collet is a tapering aperture Z). The walls of this aperture are sharply tapered, as indicated in both Figs. 1 and 2, and at the smaller end of the aperture its diameter is slightly less than the external diameter of that portion of the staff which is inserted therethrough, for a purpose to be subsequently explained. The other end of the collet is provided with a flat face If to bear against the roller-table c in a manner to be indicated.

The staff is designated as a whole by the letter dand is turned at its ends to provide the conical pivots cl d, which taper gradually from shoulders (Z (P, formed by circumferential grooves (Z d The upper portion of the staff is enlarged at d to form a prominent shoulder (Z the part (1 lying between said shoulder and the end of the staff being tapering toward the center, as shown. The enlargement (Z is substantially cylindrical and, as previously stated, is slightly greater in diameter than the internal diameter of the end (Z of the collet, so as to insure a perfect frietional engagement between the two parts. The said enlargement d is swelled at (Z to form a support for the rollertable c, which is provided with an aperture 0' adequate to re ceive said portion d That part of the balance which lies between the cylindrical flange d and the enlargement d and which is indicated at (Z may be frustoconical, as shown in Fig. 1, or else it may be omitted entirely, as shown in Fig. 2, and the flange 61" may be plane on both sides and extend abruptly from the remainder of the staff.

The flange (Z is substantially equal in axial diameter to the table 0, which fits frictionally thereon, as indicated. Vhere the flange (Z has a tapering end portion (1 as shown in Fig. 1, the collet at the end I) is internally beveled to fit thereagainst.

In placing the balance and the collet upon the staff the upper end of the latter is forced through the aperture in the collet, the smaller end I) fitting tightly around the cylindrical enlargement cl, and the staff is forced axially through the collet until its end bears firmly against the flange (1 Where the flange is beveled or tapering, as in Fig. 1, its engagement with the beveled walls of the aperture and collet centers the latter and insures that the staff shall be accurately placed in the balance. The end portion of the collet also bears against the roller-table c, which is trued relatively thereto.

Itis unnecessary, as previously stated, that the flange (1 should be provided with the tapering end b and in Fig. 2 I have shown a construction in which the end of the collet is flat and bears directly against the plane end of the flange. When the two contiguous surfaces on the collet and flange are pressed firmly together, it causes an accurate adjustment of the balance and the staff, and the parts are prevented from subsequent movement relatively to each other by the engagement of the smaller end of the collet with the cylindrical enlargement d" in the staff.

"When it is desired to remove the worn-out staff, pressure is exerted against the lower end thereof, as injury to the lower pivot need not be avoided, since the staff is to be discarded, and in inserting the new staff pressure is exerted against the shoulder (Z to drive it home. The engagement between the collet and the staff is in a line atthe smaller end of the collet, so that there is a free space between the inner walls of the collet and the enlargement d, whereby the balance and collet may be adjusted laterally with a rocking motion relatively to the staff, the engagement of said collet with the flange (Z serving to true the two parts relatively to each other.

Having thus explained the nature of the invention and described a way of constructing and using the same, although without attempting to set forth all of the forms in which it may be made or all of the modes of its use, I declare that what I claim is 1. In combination, a collet having a tapering aperture, and astaff havinga cylindrical port-ion extending through said aperture, the upper engagement between said staff and collet being only at the end of the tapering aperture through the latter.

2. In combination, a collet having a tapering aperture, and a staff having a cylindrical portion extending through said aperture, and a flange or shoulder engaging the end of said collet, the upper engagement between said staff and collet being only at the end of the tapering aperture through the latter.

8. The combination with a collet having a tapering aperture, of a staff having a cylindrical portion extending through said aperture and having also a flange or shoulder engaging the end of said collet, said flange having its upper surface beveled, and the lower end of the aperture of the collet being formed to flt the beveled portion of the flange, the diameter of the cylindricalportion above said flange being uniform.

In testimony whereof I have affixed my signature in presence of two witnesses.

DUANE H. OIIUlj-tOl l. Witnesses:

J. W. BRUCKES, E. A. Manse. 

